Yan X P, Hendry M J, Kerrich R
Department of Chemistry, Nankai University, Tianjin, China.
Anal Chem. 2000 Apr 15;72(8):1879-84. doi: 10.1021/ac9909655.
A method has been developed for the speciation of trace dissolved Fe(II) and Fe(II) in water by on-line coupling of flow injection separation and preconcentration with inductively coupled plasma mass spectrometry (ICPMS). Selective determination of Fe(III) in the presence of Fe(II) was made possible by on-line formation and sorption of the Fe(III)-pyrrolidinecarbodithioate (PDC) complex in a PTFE knotted reactor over a sample acidity range of 0.07-0.4 mol L(-1) HCl, elution with 1 mol L(-1) HNO3, and detection by ICPMS. Over a sample acidity range of 0.001-0.004 mol L(-1) HCl, the sum of Fe(III) and Fe(II), i.e., Fe(III + II), could be determined without the need for preoxidation of Fe(II) to Fe(III). The concentration of Fe(II) was obtained as the difference between those of Fe(III + II) and Fe(III). With a sample flow rate of 5 mL min(-1) and a 30-s preconcentration time, an enhancement factor of 12, a retention efficiency of 80%, and a detection limit (3s) of 0.08 microg L(-1) were obtained at a sampling frequency of 21 samples h(-1). The relative standard deviation (n = 11) was 2.9% at the 10 microg L(-1) Fe(III) level. Recoveries of spiked Fe(III) and Fe(II) in local tap water, river water, and groundwater samples ranged from 95% to 103%. The concentrations of Fe(III) and Fe(II) in synthetic aqueous mixtures obtained by the proposed method were in good agreement with the spiked values. The result for total iron concentration in the river water reference material SLRS-3 was in good agreement with the certified value. The method was successfully applied to the determination of trace dissolved Fe(III) and Fe(II) in local tap water, river water, and groundwater samples.
已开发出一种通过流动注射分离和预富集与电感耦合等离子体质谱法（ICPMS）在线联用，对水中痕量溶解态Fe(II)和Fe(III)进行形态分析的方法。通过在聚四氟乙烯（PTFE）打结反应器中，在0.07 - 0.4 mol L⁻¹ HCl的样品酸度范围内在线形成并吸附Fe(III)-吡咯烷二硫代甲酸盐（PDC）络合物，在存在Fe(II)的情况下选择性测定Fe(III)，用1 mol L⁻¹ HNO₃洗脱，并通过ICPMS检测。在0.001 - 0.004 mol L⁻¹ HCl的样品酸度范围内，无需将Fe(II)预氧化为Fe(III)即可测定Fe(III)和Fe(II)的总和，即Fe(III + II)。Fe(II)的浓度通过Fe(III + II)和Fe(III)的浓度差值获得。在样品流速为5 mL min⁻¹和30 s预富集时间下，采样频率为21个样品 h⁻¹时，获得了12的富集因子、80%的保留效率和0.08 μg L⁻¹的检测限（3s）。在10 μg L⁻¹ Fe(III)水平下，相对标准偏差（n = 11）为2.9%。当地自来水、河水和地下水样品中加标Fe(III)和Fe(II)的回收率在95%至103%之间。用所提出的方法获得的合成水性混合物中Fe(III)和Fe(II)的浓度与加标值吻合良好。河水标准物质SLRS - 3中总铁浓度的测定结果与认定值吻合良好。该方法成功应用于当地自来水、河水和地下水样品中痕量溶解态Fe(III)和Fe(II)的测定。
